Don't Fertilize Plants That Aren't Growing in Winter – One Pro Gardener Says it Damages Them in 5 Ways, and is a Waste of Time

It may be tempting for some gardeners to get a head start on spring by fertilizing plants in winter. The thinking may be that it will help plants get off to a great start for the upcoming season, and what harm can it do? The truth is that it can damage plants, as well as be a waste of time and money.

Should you fertilize plants in winter? The answer is predominantly no. There is no point in feeding plants that are not actively growing, especially if you can hurt them by doing so. In the same way as you don’t fertilize houseplants in winter if they are dormant, resist the temptation to feed outdoor plants during the coldest months.

The general rule is not to fertilize plants in winter in colder climates, for the reasons we reveal below. If you want to do something positive for your outdoor plants in winter, mulch them. But those in warmer climates can fertilize plants in winter as they continue to grow.

Can You Fertilize Plants in Winter? First, Check for Any Bans

Depending on where you live, it may be prohibited to fertilize plants in winter. Whether you want to fertilize plants in winter or not, such regulations force your hand.

These restrictions are not widespread, but the states of New Jersey and Maryland have bans on homeowners preventing fertilizing between November and March. In addition, some other states, such as New York and Florida, have local county bans that cover fertilizing lawns and plants during winter.

Always check any local restrictions where you live before using winter fertilizer on plants in your yard. However, even if it is allowed, feeding is not beneficial, and it is a waste of time and money to fertilize plants in winter.

5 Reasons Not to Fertilize Plants in Winter

If you live in cold or milder US hardiness zones, where plants go dormant for winter, and the ground freezes, you should not fertilize plants in your yard for these reasons:

1. Plants Aren’t Actively Growing

A simple rule of thumb to remember when considering fertilizing plants in winter is: if the plant isn’t actively growing, then don’t fertilize it.

Think about what fertilizer does for plants; it provides essential nutrients to help them grow, develop, and bloom strongly. When the plant is dormant, it is doing none of those, so it doesn’t need additional fertilizer during winter.

Only fertilize flower beds, shrubs, or trees when the plants are actively growing, when they need those additional essential plant nutrients that the fertilizer provides. If you fertilize plants in winter when they don’t need it, you risk encouraging growth at the wrong time, or the nutrients themselves are simply washed away and wasted.

2. It Can Encourage Undesirable Growth

There are associated risks that come with fertilizing plants in late fall or early winter. It encourages new growth at a time when plants should be concentrating their efforts on going dormant for winter.

Any new growth as a result of affecting the plant’s natural cycles is weak and easily damaged by cold weather. This frost damage can leave the plant increasingly susceptible to pests and diseases over the winter period.

A good general guideline is not to fertilize shrubs or perennials after September. Late feeding is a fertilizing mistake, and no good comes from stimulating the plant into growth at the wrong time.

3. Plants Can’t Take in Nutrients From Frozen Soil

In colder climates, there is little point in taking the time to fertilize plants in winter, as, even if they did need nutrients, they cannot benefit from them when the soil is frozen.

When soil freezes in winter, so does the water it contains. And movement of water is crucial in the conversion and absorption of nutrients by plants. As water isn’t moving and microbes in the soil are not active, the fertilizer is not converted into a usable solution or absorbed by the plant’s roots.

As plant roots take in nutrients by absorbing moisture in the soil, they cannot take anything in when the soil is frozen solid. It makes fertilizing in winter a waste of time, plus, as we’ll cover next, you cannot guarantee the nutrients remain in the soil once it thaws and the plants start to grow again.

4. Nutrients Are Wasted and Leech Away

If you fertilize plants in winter and they don’t get to take up the nutrients, then what happens to all that goodness? In an ideal world, the remaining fertilizer remains in the ground and boosts soil nutrients, to the benefit of plants when they start arising from their winter slumber.

However, the reality is usually that the fertilizer doesn’t improve garden soil or help plants, but actually poses more of a risk to the environment. The fertilizer often gets lost to water runoff when the snow melts or is leeched away during winter rainfall. The plants in your yard never get to benefit from the nutrients, but the fertilizer ends up washing away into rivers or lakes.

5. Excess Fertilizer in the Soil Can Burn Roots

If the fertilizers aren’t washed away and build up in the soil, where they are not being used or taken up by plant roots, they can reach a harmful level. Fertilizers, especially inorganic and fast-release fertilizers, contain salts that can burn plant roots if they reach too high a level.

The risk of fertilizer burn, as it is known, is high during winter when plants aren’t efficiently absorbing nutrients. Excess salts in the soil pull water out of the plant’s roots, dehydrating plants and damaging roots as they turn dry and brittle. It will also potentially cause dieback and result in sub-optimal growth in spring.

When to Fertilize Plants in Winter, and How

If you live in the warmest US hardiness zones where plants grow throughout winter, and the ground doesn’t freeze, then you can fertilize plants in winter. As long as your plants are actively growing, they will benefit from the nutrients.

In milder or colder climates, rather than fertilizing in winter, focus on developing soil health through mulching instead, as this offers great long-term benefits to plants. If you mulch flower beds and spend time mulching a vegetable garden, it brings many positives without the risk of damaging your plants.

By mulching with a thick layer of organic matter, such as compost, well-rotted manure, or leaf mold, you lock moisture into the soil, protect plant roots from frost, improve soil structure, and slowly release nutrients into the ground as the material breaks down. There is no risk of encouraging unwanted growth or burning plant roots with mulching.

As well as focusing on soil health through mulching, winter is also an ideal time of year to test your soil.

You can get valuable information on the fertility of your soil with a simple soil test kit, such as this professional soil test kit at Amazon, which gives lab analysis on the levels of 13 different nutrients in the soil.

A soil test will also give you good guidance for how to improve the quality of your soil so your plants grow to their full potential.